Effects of immuno-potent drugs and their association with an unfractionated heparin on an experimental venous thrombosis.

Immuno-potent drugs are largely used in human medicine. The aim of this study was to determine the role of two immuno-modulators (sodium diethyl-dithiocarbamate, RU 41 740) and two immuno-suppressors (methylprednisolone, cyclosporin A) alone or in association with an unfractionated heparin (Calciparin), on an experimental venous thrombosis made by vena cava ligation in male Wistar rats. Each immuno-potent drug was administered for six days before the thrombus induction at the same dosage (10mg/kg b.w.), and the Calciparin, used as treatment of the thrombosis, was administered two hours after the thrombus induction at the dose of 1mg/kg b.w. Immuno-treatment potentiated thrombus formation: the increase in thrombus weight was greater with immuno-modulators (43% on average in comparison with placebo) than with immuno-suppressors (20%). In association with Calciparin the antithrombotic effect was also potentiated and more marked with the immuno-modulators than with immuno-suppressors. An increase in circulating monocytes was observed in all groups whether Calciparin was present or not. Coagulation tests were not affected by immuno-therapy. However, immuno-modulators led to an inhibition of platelet aggregation. In conclusion, this trial seems to show a probable effect of immunological cells in thrombosis and in the antithrombotic effect of heparin, but the mechanism involved is not yet determined.